Re: [boost] [SPAM (Header)] - Re: [optional] little addition... optional_assign_to, optional_move_to, optional_swap? - Number of numbers in MIME From exceeds maximum threshold

Subject: Re: [boost] [SPAM (Header)] - Re: [optional] little addition... optional_assign_to, optional_move_to, optional_swap? - Number of numbers in MIME From exceeds maximum threshold
From: Arno Schödl (aschoedl_at_[hidden])
Date: 2009-03-06 17:41:21

> > Thus, until move semantics are practically usable (whether via 
> > Boost.Move or C++0x) I would either add the three functions as member 
> > functions, or just your optional_assign() as a free function, but not 
> > two members and one free standing.
> >
> > What do you think?
>
> FWIW, my vote would go to your first option, adding 
> optional_assign_to(T&), optional_move_to(T&), and optional_swap(T&) as 
> member functions to optional<T>.  But of course, my name isn't Arno!

I am happy with members. Just for my understanding, why are optional_swap and optional_move_to not expessible as free functions? 

template< class T, class U >
bool optional_move( T& t, boost::optional<U>& u ) {
  if( u ) {
    t=*u;
    return true;
  } else {
    return false;
  }
};

template< class T >
bool optional_move( T& t, boost::optional<T>& u ) {
  if( u ) {
    swap( t, *u );
    return true;
  } else {
    return false;
  }
};

{
        int i;
        boost::optional<int> j=1;
        optional_move( i, j ); // swaps
}
{
        double i;
        boost::optional<int> j=1;
        optional_move( i, j ); // assigns with implicit conversion
}

What am I missing?
 
Arno

--
Dr. Arno Schoedl · aschoedl_at_[hidden] 
Technical Director 
 
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